John Ging, director of operations for the U.N. Office for the Coordination of Humanitarian Affairs, said there was an urgent need for around $150 million in assistance to help those affected by conflict in Mali.
"The people of Mali have suffered appallingly," he said in a statement. "Now is the time for us to help."
The United Nations estimates that more than 430,000 people have been displaced by the Malian conflict, which grew out of a coup in early 2012.
The Malian government in January called for military support from France, its former colonial power, to help thwart the southern advance of militant forces. Control over north Mali was lost to foreign rebels and al-Qaida supporters following the coup.
French and Malian forces have retaken key cities they press north. Ging said help was needed, but the tide was turning in Mali.
"We are there, faced very directly with the immediate needs, with the urgency," he said. "Not only is the need there but also the very real opportunity to turn things around."